Bernholz, Charles D., et al. "As Long as Grass Shall Grow and Water Run: The Treaties Formed by the Confederate States of America and the Tribes in Indian Territory, 1861." 25 Aug. 2016. University of Nebraska-Lincoln, Center for Digital Research in the Humanities. 20 Sept. 2016 <http://treatiesportal.unl.edu/csaindiantreaties/>.

---. "Territorial Evolution of the United States." 10 Aug. 2016. Here an audacious attempt to convey a tremendously complex subject. In spite of careless grammatical errors in the text, the maps seem to be authoritative. There are many, and they provide a fascinating study. So far as I can determine, this is the only resource of its kind. 11 Aug. 2016 <https://en.wikipedia.org/wiki/Territorial_evolution_of_the_United_States>.